Rotatable earth borer



United States Patent ROTATABLE EARTH BORER Andreas Stihl, Badstr. 169, Neustadt, near Waiblingen, Germany Filed Feb. 6, 1958, Ser. No. 713,599

. 3 Claims. .(Cl. 175-388) The present inventionrelates to a borer for turning boring work in the deformable ground such as soil, clay, loam, loam-containing sand, loamy marl, gravel etc. for non-deep. drilling of a few yards length and for boring diameters up to approximately 4 inches.

Such drilling has frequently to be effected in dilerent directions, sometimes in vertical direction, sometimes along an inclined direction, but mostly in approximately horizontal direction in order to carry out the drilling for water mains, gas mains, electric cables, through dams, streets or building sites. Such drilling is also useful to facilitate the installation of poles in the building industry and in hydraulic engineering, in the grounding of electric wire systems and for many other purposes. Such -bore holes are effected mostly without the installation of pipes, but it is required that such bore holes must have a great resistance against collapse for a certain time. Furthermore, such bore holes must be able to be produced by light portable devices.

Portable rotatable devices have been developed by means of which with the aid of an internal combustion eng-ine of a few horsepower it is possible to bore holes of small diameter in diierent directions. These devices employ rotatable spiral-shaped drills, and the cut-out mud, soil or the like is moved yout of the bore being drilled along the rod system of -the drilling device. However, the thus produced bore holes have a relatively rough and non-compacted wall. Therefore, when or before pipes or cables are passed through such bores, the bores easily collapse or soil breaks off into the bore so that the above mentioned heretofore known portable devices are not suitable in many types of soil for the purposes referred to above.

Therefore, drilling devices have been developed which operate in a beating or pushing manner. These devices press the cut-out soilmaterial into the wall of the bore hole thereby imparting an increased streng-th upon the same. However, these devices are relatively heavy and expensive and their employment does not pay for short time operations, particularly since generally they have to be driven by compressed air or electric current and consequently are not as universally applicable as devices with an easily transportable internal combustion engine. Furthermore, drills which are hydraulically advanced have the tendency when hitting upon harder matter to evade in the direction of the least resistance, i.e. generally upwardly. This lifts the street pavement which, of course, must be avoided. A rotatable drill does not have these drawbacks at least not to the same extent.

lt is, therefore, an object of the present invention to provide a rotatable earth borer which will overcome the above mentioned drawbacks.

It is another object of' this invention to provide a rotatable earth borer which can easily be employed in connection with portable boring devices driven by an internal combustion engine and -which will furnish strong bore holes in a short time.

It is another object of this invention to provide an Y latter can advance.

r"rice earth borer of the type set forth in the preceding paragraphs, which'can easily be manufactured and is rela-4 tively inexpensive.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in

Fig. 2 shows the earth borer of Fig. l but turned about Y its longitudinal axis by Fig. 3 is a section along the line III-III of Fig. 2. Fig. 4 is a section along theline IV-IV of Fig. 2. Fig. 5 is a section along the line V-V of Fig. 2. Fig. 6 is a section along the line VI-VI of Fig. 2. Fig. 7 is a section along the line VII-VII of Fig. 2. Fig. 8 is a section along the line VIlI-VIII-of Fig. 2. Fig. 9 is a view of a borer somewhat modified over that of Fig. 1. v

Fig. 10 illustrates on an enlarged scale a cross section through the borer of Fig. 2 along the line VI-VI thereof and shows its working position within the bore hole.

The present invention is based on the principle of rotatingin the bore hole bodies with less curvature than that of the bore hole so that Ithese bodies tangentially contact the bore hole wall from the inside. These bodies furthermore have an outer contour corresponding to that of a slender cone.- As a result thereof, the rotating drill presses the stone dust or cut material toward the outside, and the closer the 'cut material gets to the bore hole wall, the greater will be the force which presses the said cut material into the bore hole wall. With purely tangential contact of the pressing body with the bore hole wall, theoretically the force infinite would be obtained for the smallest grains. However, also with the prevailing grain sizes, the pressing force is still high enough to cause the cut-out material completely to penetrate into the bore hole wall and thereby to strengthen the same by pressing.

Referring now to the drawing in detail, the borer according to the invention may be connected to the drilling rod system or to the pipe system, in case such should be retained in the bore hole, by means of a coupling known per se and provided with a stud 1, a groove 2, jaws 3 and shank 4. The borer is provided with a collar 6 having connected thereto two semi-pipes 7 and 8. As will be evident from the drawing, the lower portion of said semi-pipes 7 -and 8 merges into a rod 9 the lower end of which carries a pre-cutter 10 known per se.

When this borer is pressed into the bore hole and is simultaneously rotated, the stone pieces or sand grains or clay lumps S (Fig. 10) move between the bore hole wall 11 and the convex surfaces of the semi-pipes 7 and 8 and due to the increasing wedging effect during the rotation are pressed under high force into the wall 11. Due to a further pressing-in of the borer, the bore hole diameter is due to the said wedging effect increased further up to the diameter of the collar 6 so that also the Inasmuch as the subsequent drilling rod system or a pipe system has -a smaller diameter than .the collar 6, the said drilling rod system or pipe system will not get caught inthe rock or sand or the like so that, whenever desired, the borer can be pulled back toward the rear out of the bore hole. In certain exceptional cases, the borer together with the pipe system may be introduced into the bore hole and remain therein inasmuch as it is not expensive. Thus, the borer according to the present invention will produce a strong bore hole wall in a simple and cheap manner.

The structure described so far, may also be varied. vFor example in some instances, also a yborer according to Fig. 9 may be employed the upper part of which up to the 3 collar 6 is identical with that of Fig. 1. In contrast to Fig. 1, the borer according to Fig. 9 Iis below the collar 6 provided with a solid metal cone with a welded-on spiral 12. This borer has the advantage that it automaticallytpnlls thedrilling rod systeminto the borehole.`

However, its pressingeiect,towardthe outside islnot `very high inasmuch as the wedging effect produced;y by the convex surfaces of the semifpipes7 'andSof the borerof Fig1 is missing in the borer of AFig 9.

It isalsoA possibleto provide a borer in which the semipipes 7 and 8 are replaced by rollers or drums of the same diameter. Such a borer will due to theldecreased friction work even better but precisely in thesamemanner as the borerraceordingto Fig. 2, However, `theprovisionof the bearings for such rollers or drums. is, of.; course, less simpleandtherefore willbe selected primarily for bores of Alarger diameter.

It is, of course, to beunderstood thatthe presentinventionis, byno means, limited toV the-particular constructions shown in the drawing `but also comprisesany modications `within the scope of the appended claims.

What I claim is:

1. An earth borer for use in connectionl -with rotary drilling operations in deformable soil, especially clay, loam, loamy marl, loamy sand and gravel, which comprises: coupling means arranged at one end of said borer 4, for connection with a drive, a pre-cutter arranged at thc other end of said borer, a. collar connected to said borer and arranged between said pre-cutter and said coupling means, Ia plurality of semi-tubular members connected to said collar and converging toward said pre-cutter while merging therewith, said semi-tubular members being so arranged that one edge of their convex outside tangentially contacts the interior of the wall `of the bore hole being drilled.

2. An earth borer according to claim 1 wherein the outermost edge oft the4 semi-tubular: members r protrudes radially outward somewhat beyond the periphery of the collar.

3. An earth borer according to claim 1 wherein that portion of the semi-tubular members which is adjacent the collar protrudes radially outward somewhat beyond the periphery of said collar.

References Cited inthe'le of this patent UNITED STATES PATENTS 334,919 Wickizer ,Jan, 26, 1886 602,339 Lawton Apr. 12, 1898 975,020 Coplen Nov. 8, 1910 1,269,970 Smith June 18, 1918 1,546,630 Deavers July 21, 1925 1,861,632 H'aynie June 7, 1932 

